Multi-branched polypropylene

Abstract

Multi-branched polypropylene having a g′ of less than 1.00.

The invention claimed is: 
     
       1. Polypropylene having a multi-branching index (MBI) of at least 0.15,
 wherein the multi-branching index (MBI) is defined as the slope of strain hardening index (SHI) as a function of the logarithm to the base 10 of the Hencky strain rate (lg(dε/dt)), 
 wherein dε/dt is the deformation rate, ε is the Hencky strain, and the strain hardening index (SHI) is measured at 180° C., 
 wherein the strain hardening index (SHI) is defined as the slope of the logarithm to the base 10 of the tensile stress growth function (lg(η E   + )) as a function of the logarithm to the base 10 of the Hencky strain (lg(ε)) in the range of Hencky strains between 1 and 3, 
 wherein the polypropylene has been produced in the presence of a catalyst system comprising an asymmetric non-silica supported catalyst, and 
 wherein the polypropylene has a strain hardening index (SHI@1 s −1 ) of at least 0.40 measured by a deformation rate (dε/dt) of 1.00 s −1  at a temperature of 180° C. 
 
     
     
       2. Polypropylene according to  claim 1 , wherein the polypropylene has a branching index g′ of less than 1.00. 
     
     
       3. Polypropylene according to  claim 1 , wherein the polypropylene has melt flow rate MFR 2  measured at 230° C. in the range 0.01 to 1000.00 g/10 min. 
     
     
       4. Polypropylene according to  claim 1 , wherein the polypropylene has mmmm pentad concentration of higher than 90%. 
     
     
       5. Polypropylene according to  claim 1 , wherein the polypropylene has a melting point Tm of at least 125° C. 
     
     
       6. Polypropylene according to  claim 1 , wherein the polypropylene is multimodal. 
     
     
       7. Polypropylene according to  claim 1 , wherein the polypropylene is a propylene homopolymer. 
     
     
       8. Polypropylene according to  claim 1 , wherein the polypropylene is propylene copolymer. 
     
     
       9. Propylene according to  claim 8 , wherein a the comonomer of the propylene copolymer is ethylene. 
     
     
       10. Polypropylene according to  claim 9 , wherein the total amount of comonomer in the propylene copolymer is up to 30 wt %. 
     
     
       11. Polypropylene according to  claim 8 , wherein the propylene copolymer comprises a polypropylene matrix and an ethylene-propylene rubber (EPR). 
     
     
       12. Polypropylene according to  claim 11 , wherein the ethylene-propylene rubber (EPR) has an ethylene content of up to 50 wt %. 
     
     
       13. Polypropylene according to  claim 1 , wherein the polypropylene is a propylene copolymer comprising a polypropylene matrix and up to 70 wt % of an ethylene-propylene rubber (EPR). 
     
     
       14. Polypropylene according to  claim 1 , wherein the catalyst system has a porosity of less than 1.40 ml/g, as determined according to DIN 66135. 
     
     
       15. Polypropylene according to  claim 14 , wherein the asymmetric catalyst is dimethylsilandiyl [(2-methyl-(4′-tert-butyl)-4-phenyl-indenyl)(2-isopropyl-(4′tert-butyl)-4-phenyl-indenyl)] zirconium dichloride.